Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

• -dioctylfluorene)-alt-5,5'-bithiophene/PS-βCD] (PDOF-BTc) polyrotaxane copolymer, through a Suzuki coupling reaction between the 5,5'-dibromo-2,2'-bithiophene (BT) inclusion complex with persilylated β-cyclodextrin (PS-βCD), and 9,9-dioctylfluorene-2,7-bis(trimethylene borate) (DOF) as the blocking group. The

• morphology and thermal properties of the PDOF-BTc rotaxane copolymer compared to its noncomplexed PDOF-BT homologue. In contrast, the number-average molecular weight (Mn) of PDOF-BTc rotaxane copolymer indicated lower values suggesting that the condensation reaction is subjected to steric effects of the

• bulkier silylated groups, affecting the ability of the diborate groups from the DOF molecule to partially penetrate the PS-βCD cavity. Keywords: alternating fluorene-bithiophene copolymer; cyclodextrins; interlocked molecules; macrocycles; persilylated β-cyclodextrin; polyrotaxanes; Introduction Organic

Restructuring polymers via nanoconfinement and subsequent release

• Alan E. Tonelli

Beilstein J. Org. Chem. 2012, 8, 1318–1332, doi:10.3762/bjoc.8.151

• ICs are formed with block copolymers or with two or more different homopolymers, the resulting coalesced samples can exhibit intimate mixing between the copolymer blocks, or between entire homopolymer chains. Each of the distinct behaviors observed for polymers coalesced from their ICs is a

• -nucleated PET not only possesses improved properties, but contains no incompatible additives, and so may be readily recycled. Coalesced block copolymers The triblock copolymer PCL-PPG-PCL, with noncrystallizable central poly(propylene oxide blocks), was synthesized by coordinated ring-opening polymerization

• of ε-caprolactone with PPG-diol as the initiator [21]. In the IC of PCL-PPG-PCL formed with α-CD, only PCL blocks were included. In contrast, both PCL and PPG blocks were included in the IC of PCL-PPG-PCL formed with γ-CD, which has larger channels. Consequently, coalescence of the triblock copolymer

Synthesis and characterization of a novel carboxyl group containing (co)polyimide with sulfur in the polymer backbone

• Miroslav Mrsevic,
• David Düsselberg and
• Claudia Staudt

Beilstein J. Org. Chem. 2012, 8, 776–786, doi:10.3762/bjoc.8.88

• all synthesized (co)polyimides, as expected. Gibbs et al. already showed in 1958, that the glass-transition temperature is affected by the rigidity of the polymer backbone [30] and that the glass-transition temperature of a copolymer is a linear function of the composition of the copolymer [31

• results in higher Tg values for this copolymer series. Additionally, Figure 5 shows that the Tg values of both synthesized (co)polyimide series increase with increasing DABA content and follow the predicted linear trend. The reason for this increase is that the DABA monomer exhibits fewer freely rotatable

• of the postulated effects, the results obtained for the synthesized (co)polyimides were compared to those of the reference copolymer 6FDA-4MPD/6FDA-DABA m:n. The Tg values of this (co)polyimide correlate very well with the postulations from Gibbs et al. and Endrey [30][31][32]. The glass-transition

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• used to inoculate individual wells of the deep-well plates, with each well containing 3 mL medium. In initial experiments, the medium was supplemented with 0.6% (w/v) of the siloxylated ethylene oxide/propylene oxide copolymer Q2-5247 (Dow Corning, USA), which acts as an oxygen carrier and has been

Azobenzene dye-coupled quadruply hydrogen-bonding modules as colorimetric indicators for supramolecular interactions

• Yagang Zhang and
• Steven C. Zimmerman

Beilstein J. Org. Chem. 2012, 8, 486–495, doi:10.3762/bjoc.8.55

• syntheses. With regard to applications, the DAN·UG (DeUG) heterodimer has been used to drive the formation of: (1) polymer blends [37], (2) a supramolecular multiblock copolymer with a high propensity for alteration [38], and (3) a supramolecular ABC triblock polymer [39]. Further, a structure–property

Synthesis and photooxidation of styrene copolymer bearing camphorquinone pendant groups

• Branislav Husár,
• Norbert Moszner and
• Ivan Lukáč

Beilstein J. Org. Chem. 2012, 8, 337–343, doi:10.3762/bjoc.8.37

• synthesized from (±)-10-camphorsulfonic acid either by a known seven-step synthetic route or by a novel, shorter five-step synthetic route. MCQ was copolymerized with styrene (S) and the photochemical behavior of the copolymer MCQ/S was compared with that of a formerly studied copolymer of styrene with

• properties of styrene copolymers formed from BZ-containing monomers, a CQ-bearing monomer (±)-10-methacryloyloxycamphorquinone (MCQ) (another monomer with a 1,2-dicarbonyl moiety) was prepared and copolymerized with styrene to give MCQ/S copolymer bearing CQ pendant groups. Enantiopure MCQ is known from the

• literature are pure enantiomers. The racemates can crystallize as a racemic mixture (lower mp), as a racemic compound (lower or higher mp), or rarely as a racemic solid solution (slightly lower or higher mp). Polymerization As introduced in Supporting Information File 1, the copolymer MCQ/S was synthesized

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• (benzimidazolyl)pyrazines 70 (Figure 13; [75][77]) represent further examples of interesting polymers functionalized with benzimidazole-based CT chromophores. Unfortunately, no NLO properties were investigated. In 2002, Kudryavtsev et al. reported third-harmonic generation in copolymer films (polyamides

Chiral recognition of ephedrine: Hydrophilic polymers bearing β-cyclodextrin moieties as chiral sensitive host molecules

• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1516–1519, doi:10.3762/bjoc.7.177

• reported recently, the CD containing NIPAAm copolymer 1 exhibits lower critical solution temperature (LCST) behavior in water [23]. As expected, the supramolecular system 2 turned out to be soluble in cold water only below the LCST of 32 °C. However, due to the presence of relatively hydrophilic ephedrine

• . Therefore we conclude that (+)-ephedrine is preferred in complexation with CD, due to a thermodynamic effect. Additionally turbidity measurements showed a slight difference between the pure copolymer and the supramolecular structure of 3 °C, but no enantiomeric effect was observed. Experimental (1S,2R

• copolymer 1 and 60 mg of β-CD in alkaline D2O. Turbidity experiments were performed on a Tepper cloud-point photometer TP1. The relative transmission of a laser beam with a wavelength of 670 nm was recorded for each experiment. The measurements were performed within a temperature range between 5 and 40 °C

Chiral recognition of macromolecules with cyclodextrins: pH- and thermosensitive copolymers from N-isopropylacrylamide and N-acryloyl-D/L-phenylalanine and their inclusion complexes with cyclodextrins

• Sabrina Gingter,
• Ella Bezdushna and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 204–209, doi:10.3762/bjoc.7.27

• -isopropylacrylamide (NIPAAm). The resulting copolymers 3D and 3L exhibit a lower critical solution temperature (LCST) of 25 °C. As a further benefit, the presence of a free carboxylic group in the copolymer system gives a high sensitivity to the pH value in respect to the LCST value. The enantioselective recognition

• conditions (Scheme 1). The molar weight distribution of polymers 3D and 3L were determined by gel permeation chromatography (GPC) after silylation of the free carboxylic groups with trimethylchlorosilane. The resulting copolymer 3D, 3L (1:20) is soluble in water below the critical solution temperature (LCST

• 3D, 3L (1:20) copolymer, whereas the 3D, 3L (1:10) copolymer is relatively hydrophobic and not water-soluble. Surprisingly, the polymers 3D, 3L (1:10) become water-soluble due to host–guest interaction with RAMEB-CD yielding 4D and 4L. To confirm the formation of the proposed inclusion complexes

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• copolymerized with styrene to yield functionalized particles [34][35] and their uptake by cells was studied [34]. In general, with increased functional groups, an increase in the uptake into cells could be observed. Copolymer particles of styrene and acrylic acid were used to encapsulate a platinum(II) complex

• -aqueous polymerizations in methanol with the same catalysts. The emulsion and miniemulsion processes were compared for the copolymerization of ethylene with vinyl acetate [66]. For batch processes, ethylene incorporation in the copolymer was found to be higher in miniemulsion than in emulsion due to the

• low solubility of ethylene in water and hence its poor transfer through the continuous phase. The use of semibatch processes reduced the difference between emulsion and miniemulsion polymerization in term of incorporation of ethylene in the copolymer. Instead of miniemulsified catalyst, functionalized

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• were used as the initiator for the ring-opening polymerization of ε-caprolactone to produce a graft copolymer. Keywords: addition oligomerization; epoxide-amine adducts; microwave; ring-opening polymerization; transfer hydrogenation; Introduction In the last decade the use of microwave (MW

• higher molecular weight products. Ring-opening polymerization of ε-caprolactone The epoxide-amine adduct 4 was used for preparation of graft copolymer 6 via ring-opening polymerization (ROP) of ε-caprolactone (ε-CL, 5), where the secondary hydroxy groups of 4 act as the initiator. This ROP was catalyzed

• formation of ester units was confirmed by the appearance of two strong bands at 1721 and 1176 cm−1 associated with C=O and C-O stretching vibrations, respectively. To prove the existence of grafted polymer 6, GPC-measurements were carried out. Figure 5 shows the GPC curves of copolymer 6 detected by UV

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• , nanoparticulate biocatalysts that can easily be separated magnetically. The enzymatic activity of the obtained biocatalyst system can be influenced by outer stimuli, such as temperature and external magnetic fields, by utilizing the LCST of the copolymer shell. Keywords: biocatalysis; biolabelling; core–shell

• nanoparticle cores with a thermoresponsive poly[oligo(ethylene glycol) methyl ether methacrylate] copolymer shell [17][18][33][34] and covalently attached protease trypsin as the biocatalytically active species. A reversible shell collapse at elevated temperatures is made responsible for significantly enhanced

• water. By proper choice of the copolymer composition, the thermoflocculation temperature of the core–shell particles can be adjusted [34][35]. The biocompatibility of poly(ethylene glycol) derivates is helpful to obtain nanoparticles acceptable for use in in vitro biological systems. The direct

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• polymer in solution was bathochromically shifted by 12 nm with the maximum at 488 nm. The polymer also showed a bright red fluorescence with the maximum at 544 nm. In addition to the alternating copolymer, copolymers with lower DPP content were also prepared. All copolymers showed the DPP absorption at

• nematic and smectic enantiotropic phases. In the same year, the first study on electroluminescent (EL) properties of a DPP-containing conjugated polymer was reported by Beyerlein et al. [28] who studied a DPP-dialkoxyphenylene copolymer in a multilayer device of ITO/DPP-polymer/OXD7/Ca/-Mg:Al:Zn and

• increasing DPP content the EL colours varied from orange to red corresponding to CIE coordinates from (0.52, 0.46) to (0.62, 0.37). The best performance was achieved for an orange emitting device with a copolymer containing only 1% DPP units. The EQE was 0.45%, the maximum brightness 520 cd m−2. At high DPP

Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

• Cathrin Corten,
• Katja Kretschmer and
• Dirk Kuckling

Beilstein J. Org. Chem. 2010, 6, 756–765, doi:10.3762/bjoc.6.89

• radical polymerization (CRP), based on the idea of reversible chain termination, decreases the disadvantage of the free radical polymerization and permits the synthesis of defined block copolymer structures [13]. The growing demand for well-defined and functional soft materials in nanoscale applications

• the inner core) [33]. Armes et al. described the synthesis of a diblock copolymer with two weak polybases (poly(2-(N-morpholino)ethyl methacrylate-block-2-(diethylamino)ethyl methacrylate) PMEMA-block-PDEA) via group transfer polymerization. By adjusting the pH value of the solution, it was possible

• smaller elution volume relative to the macroinitiator indicated successful block copolymer formation. No shoulder or second peak at elution volumes for macroinitiator was found, indicating that most of the polymers possessed intact structure. Additionally, the SEC traces show an overlap between the two

Calix[4]arene-click-cyclodextrin and supramolecular structures with watersoluble NIPAAM-copolymers bearing adamantyl units: “Rings on ring on chain”

• Bernd Garska,
• Monir Tabatabai and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 784–788, doi:10.3762/bjoc.6.83

• intermolecular electrostatic repulsion. Accordingly, the hydrodynamic diameter of 4 decreased in NaOH solution from 150 nm to 9.0 nm, which can actually be attributed to the existence of trimers. Host–guest complexion of 4 and 5 An adamantane containing copolymer 5 was prepared via free radical polymerization of

• 6-acrylamido-N-adamantyl-hexane amide and NIPAAM. Copolymer 5 was mixed with 4 subsequently (Scheme 2) to form supermolecular structures. The hydrodynamic diameter of copolymer 5 increased from 8.5 nm to 53 nm after addition of 4. This clearly indicates the inclusion of a polymer attached adamantane

• as an intermolecular linker between the copolymer chains. To prove the assumed agglomeration of the CD-moieties in water [17], adamantyl carboxylate was added to the solution as a competitive guest molecule. As expected, a decrease of the hydrodynamic diameter from 53 nm to 13 nm was observed

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine)

• Katja Hofmann,
• Ingolf Kahle,
• Frank Simon and
• Stefan Spange

Beilstein J. Org. Chem. 2010, 6, No. 79, doi:10.3762/bjoc.6.79

• hydrolyzed PVFA contains ca. 5% of formamido groups and 95% of primary amino groups. The water-soluble PVAm copolymer has been widely applied for a number of purposes, e.g., in catalysis [7], chelation [8], treatment of waste water [9], paper making [10], recovery of oil [11] and as superabsorber [12

• experiments. Hence, the synthesis of a fluorescent hybrid material was possible. Experimental General details: The aqueous solution of poly(vinyl amine) copolymer (Mn = 15,000 g mol−1, pH = 11) was kindly provided by BASF SE (Ludwigshafen, Germany). 2,6-O-β-dimethylcyclodextrin (β-DMCD) was supplied by Wacker

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• compared to the homopolymer PGA should lead to simplified processing conditions. The findings contribute to broadening the range of biomedical applications of PGA. Keywords: block copolymer; hyperbranched; PGA; polyester; polyglycerol; poly(glycolide); star polymer; Introduction Linear aliphatic

• PG is believed to play an important role in the properties of the resulting star block copolymer, the branched topology and the distribution of OH groups therein are key factors that will also be addressed in the following text. Careful drying of the PG cores under vacuum is a crucial step for the

• via calibration with polyethylene glycol (PEG) standards. The obvious underestimation of the molecular weight by SEC is attributed to the peculiar spherical geometry of the multi-arm star copolymer and has also been observed with other star polymers. The polydispersities of the materials are in the

RAFT polymers for protein recognition

• Alan F. Tominey,
• Julia Liese,
• Sun Wei,
• Klaus Kowski,
• Thomas Schrader and
• Arno Kraft

Beilstein J. Org. Chem. 2010, 6, No. 66, doi:10.3762/bjoc.6.66

• mol %; the balance to 100 mol % was made up by NIPAM. For example, S10CH10 means that this RAFT copolymer was made from sodium methacrylate (10 mol %), N-cyclohexylacrylamide (10 mol %), and NIPAM (80 mol %). RAFT polymerizations were carried out in methanol at 60 °C for 48 hours in the presence of

• calculated using the Savitzky–Golay algorithm [17][18][19]. The second derivative is a useful method of refining the spectra to reveal subtle changes in the UV–vis absorption plot. The UV titration of a typical RAFT copolymer into a solution of cytochrome C in a phosphate buffer (pH 7, 0.15 M KCl) showed

• × 104 M−1) was only detected with S20CH15, which carries twice the amount of carboxylate groups. Association constants were initially calculated for each 1:1 complexation event of a single protein by the copolymer [20]. However, even with S20CH15, no binding was detectable with hemoglobin, confirming an

Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water

• Helmut Ritter,
• Beate E. Mondrzik,
• Matthias Rehahn and
• Markus Gallei

Beilstein J. Org. Chem. 2010, 6, No. 60, doi:10.3762/bjoc.6.60

• MALDI-TOF which indicated a mass of 6172.7 [M+Na]+. Very recently a paper was published, reporting the expected LCST properties of the copolymer consisting of N-allylferrocenecarboxamide and N-isopropylacrylamide (poly(NiPAAM/FCN)) [26]. However, in this instance the copolymer was prepared by a

• classical synthesis in an organic solvent. Thus, we were encouraged to prepare a similar copolymer by free radical polymerization in water starting from cyclodextrin complexed vinylferrocene 1 and the water-soluble co-monomer N-isopropylacrylamide 5, the latter in a 20 fold molar excess. The copolymer

• (cp) + 3.52 ppm (2) in 1H1H ROESY-NMR spectrum. The LCST of the copolymer in water was slightly increased from 17 °C to 19 °C (Figure 4) after the addition of cyclodextrin. Conclusion It can be concluded from the experiments described above that vinylferrocene can be easily polymerized in water after

Synthesis and crossover reaction of TEMPO containing block copolymer via ROMP

• Olubummo Adekunle,
• Susanne Tanner and
• Wolfgang H. Binder

Beilstein J. Org. Chem. 2010, 6, No. 59, doi:10.3762/bjoc.6.59

• polymerization in comparison to U1. The synthesis of block copolymers with molecular weights up to Mn = 31 000 g/mol with low polydispersities (Mw/Mn = 1.2) is reported. Keywords: block copolymer (BCP); crossover reaction; MALDI; NEOLYST™; ROMP; Introduction Block copolymers are macromolecules composed of

• and 9, initiated via the catalysts U1–U3, as well as mass spectrometric investigations of the crossover reactions via MALDI methods. The incorporation of the free radical 9 into block copolymer is an important contribution in the generation of polymers for reversible charge storage materials, as

• synthesis of the BCP was achieved by use of this initiating system to yield the respective BCP-A10T10, A20T20, A25T25 and A50T50 with the expected molecular weight and with low polydispersity (see Table 1, entries 18–21). The GPC traces of A25 block and the A25T25 block copolymer are shown in Figure 7

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• poly(propargyl acrylate-co-N-vinyl pyrrolidone). These glycopolymers were used as polymer surfactants, in order to obtain glycosylated polycaprolactone nanoparticles. Optimum stabilization for long time storage was achieved by using a mixture of glycopolymers and the non-ionic triblock copolymer

• nanoparticles, thus increasing their circulation in the body. The polyether triblock copolymer PEO-b-PPO-b-PEO Pluronic® F-68 (PF-68) is approved by the US Food and Drug Administration and is thus widely used in pharmaceutical formulations. Glycopolymers can advantageously replace these block copolymers. In

• pyrrolidone) as the starting copolymer. Poly(NVP) is known to be biocompatible and to promote adhesion. NVP-based maleic copolymers have been reported for BSA immobilization [14] as well as for the preparation of polymer nanoparticles [10][15]. The choice of the carbohydrate moieties to be grafted onto the

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• copolymer poly(M1-b-M2)-Rh containing 18 mg of Rh(I)/g of block copolymer with a cmc of 2.2 × 10−6 mol L−1. The Rh-loaded polymer was used for the hydroformylation of 1-octene under micellar conditions. The data obtained were compared to those obtained with a monomeric analogue, i.e. CH3CON(Py)2RhCl(COD

• catalysis in one system. Thus, with catalysts permanently linked to the block copolymer, metal leaching is substantially reduced and allows for the separation/reuse of the catalyst [1][2][3][4][5][6][7]. In cases where reactions are run in polar media, the catalyst is best located inside the hydrophobic

• micellar core, where, upon micelle formation of the functionalized block copolymer, the monomer will also accumulate. This leads to high educt concentrations at the polymer-bound catalyst, often resulting in high reaction rates in water [8]. We recently reported on the synthesis of RhI and IrI complexes of

Chemoselective reduction of aldehydes by ruthenium trichloride and resin- bound formates

• Basudeb Basu,
• Bablee Mandal,
• Sajal Das,
• Pralay Das and
• Ashis K. Nanda

Beilstein J. Org. Chem. 2008, 4, No. 53, doi:10.3762/bjoc.4.53

• first example of the use of a simple, phosphine-free, RuCl3-DMA catalytic system in H2-hydrogenation of dimethyl ester of protoporphyrin IX to the mesoporphyrin analogue [14]. Catalytic activity of styrene-divinyl benzene copolymer-bound Ru(III)-EDTA complex was also studied in H2-hydrogenation of

Hydrogen bonding patterns in the cocrystals of 5-nitrouracil with several donor and acceptor molecules

• Reji Thomas,
• R. Srinivasa Gopalan,
• G. U. Kulkarni and
• C. N. R. Rao

Beilstein J. Org. Chem. 2005, 1, No. 15, doi:10.1186/1860-5397-1-15

• resembles the quadruple hydrogen bond pattern found usually in copolymer and peptide structures. [28][29][30] The two tape structures alternate in a layer with C-H...O bonds from the methyl group connecting them. Interlayer contacts (see Figure 6b) are of the type, C-H...O and C-H...N (H(61B)...O(2), 2.324